元谋干热河谷5种牧草凋落物分解动态研究

Dynamics of Forage Litter Decomposition in Yuanmou Dry-hot Valley

选择元谋干热河谷常见的5种禾本科和豆科牧草为材料,研究其凋落物对时间、温度和湿度的分解动态。结果表明;豆科牧草凋落物分解整体明显快于禾本科牧草;牧草凋落物的分解可能和牧草的粗纤维和饱和含水量存在一定的相关性。斯皮尔曼相关分析表明,禾本科牧草凋落物降解与温度成显著正相关(P<0.10);而豆科牧草凋落物降解与温度、所有供试牧草凋落物与湿度的相关性均不显著。不同科和同一科不同种牧草凋落物分解对温度的响应不同;禾本科牧草凋落物均在最高温度下达到最大分解量,而豆科牧草随着温度增加整体呈现一种先增加后减少的单峰曲线变化趋势。不同科和同一科不同种牧草凋落物分解对湿度的响应也不同,孔颖草(Bothriochloa pertusa)和热研8号坚尼草(Panicum maximum‘Reyan No.8')星单峰曲线的变化模式;而百喜草(Paspalum notatum)和豆科牧草随着湿度增加呈现双峰曲线的变化模式,但出现高峰的湿度明显低于豆科牧草。

Five kinds of gramineous and leguminous forage grasses （Bothriochloa pertusa, Paspalum nota- turn, Panicum maximum ＇ Reyan No. 8＇, Stylosanthes guianensis ＇ Reyan No. 5 ＇, Neonotonia wightii ＇Tinaroo＇） were selected in Yuanmou dry-hot valley and the litter composition dynamics of forage grasses was studied with different times, temperature and relative humidity. Results showed that the litter decom- position of leguminous forage was faster than that of gramineous forage obviously. Litter composition was probably related to crude fiber content and saturation moisture content. Spearman correlation analysis indi- cated that the litter decomposition of gramineous forage had a significant positive correlation with tempera- ture （P^0.10）, whereas there were no significant relation between the litter decomposition rate of legu- minous forage and temperature, the litter decomposition rate of all tested forage and relative humidity. The litter decomposition rate of gramineous forage reached the maximum at the highest temperature. The litter decomposition rate of leguminous forage first increased and then decreased with temperature increas- ing. The litter decomposition models of Bothriochloa pertusa and ＇Reyan No. 8＇ were similar, which was a nonlinear curve with single peak. However, the litter decomposition models of Paspalum notatum and leguminous forage were similar with relative humidity increasing, which was a nonlinear curve with two single-peaks. The optimal relative humidity of Paspalum notatum litter decomposition was lower than that of leguminous forage.